MMHA guidebook on secondary units in existing homes.
This guidebook was developed with input from the Large Municipal Chief Building Officials Group, Ontario Building Officials Association and the Ontario Association of Fire Chiefs.
https://news.ontario.ca/mma/en/2019/09/ontario-taking-further-action-to-build-more-housing.html
https://files.ontario.ca/mmah-adding-a-second-unit-in-an-existing-house-en.pdf